In typical database systems, Information with respect to any facilities, including railway installations, road facilities, and river facilities may be managed as data, which corresponds to a predetermined origin coordinate with a distance therefrom to a building (sometimes referred to as mileage data). More specifically, facility information may include the construction date, management number, structure information such a wall thickness for example and so on. The information about the buildings may be managed so as to relate the distance from a predetermined origin to the start point of the facility and to the end point of the facility. For example, a bridge has a first end or start point and also a second end or end point.
When the above described facility information is stored in a database, an information retrieval search may be performed by using the name or distance of, for example, a building as a search key. In this search method although the distance to the building will be found, its geographical position will not be clear. For example, searching on a map is required to find the exact position. Thus, in order to find the position and contents of a facility, it is necessary to perform a retrieval search on not only a database but also a reference to a map. In such a method, the identification of a position for example in case of an occurrence of damage to a facility has not been easily performed.
Moreover, even when both the facility data and the map data are computerized, since these data sets are not related to each other, there will be no guarantee that an update to the one will be reflected to the other. When an update of the one is not correctly reflected to the other, there can be inconsistencies between data sets. In such a case, the reliability of the map data and facility data will be ultimately degraded.
Therefore, the facility data and map data are required to be reliably related so as to allow finding the position of a building on a map, and to be updated correctly so as to have no inconsistency between the facility data and map data.